wireless problem

I have a belkin wireless card that no longer connects to the internet, although it worked for months before. The signal is strong, my computer says the device is working properly, I can download from bittorrent and limewire but can't connect through a browser. I am running vista, and yesterday I bought and installed a new wireless card and have the same problem. I called belkin support and they said adjust the settings on my router, but if I never changed them why would it stop working? Has anyone seen this before? Thanks, all.